Depth controllable and measurable medical driver devices and methods of use

ABSTRACT

Disclosed are devices and methods for creating a bore in bone. The devices and methods described involve controlling the drive and measuring the work of a working tool such that a user can avoid injuries to surrounding structures.

REFERENCE TO PRIORITY DOCUMENTS

This application is a continuation of co-pending U.S. application Ser.No. 13/077,794 filed Mar. 31, 2011, which claims the benefit of priorityto U.S. Provisional Patent Application Ser. No. 61/319,771, filed onMar. 31, 2010; and U.S. Provisional Patent Application Ser. No.61/333,685, filed on May 11, 2010; and U.S. Provisional PatentApplication Ser. No. 61/421,596, filed on Dec. 9, 2010. Priority of thefiling dates and the disclosures of the patent applications are herebyincorporated by reference in their entirety.

BACKGROUND

Orthopedic surgery can require bone drilling for the repair of fracturesor insertion of implants or other devices. The resulting holes can beused to accept screws, implants and other devices to exert pressure,fixation or reduction of the bone or to place prosthetic joints or otherimplants. Other medical procedures can require access to bone. Forexample, the interosseous canal of bone can be accessed to allow fluidadministration. Bone can also be accessed to allow the harvesting ofbone, collection of bone marrow cores, or for the aspiration of bonemarrow for diagnostic or therapeutic purposes. During any procedurewhere a drill or other driver is used to advance a tool into and throughbone, the user must consciously and carefully limit the penetration tothe desired depth. If the user allows the tool to penetrate further, thepatient can suffer injury to distal structures such as nerve, brain,spinal cord, artery, vein, muscle, fascia, bone or joint spacestructures. These types of injuries can lead to severe patient morbidityand even death. The devices inserted to a drilled bore often must fitwithin a narrow length range that can vary sometimes by no more than amillimeter or less.

Once the drilling of a bone is safely complete, it is often prudent toobtain the depth of the bore made by the drilling tool. Many proceduresrequire knowledge of the depth of tool penetration, such as in theplacement of internal fixation devices, screws and other implantablehardware. Selecting an appropriate length of the screw or other implantnecessary for the procedure depends upon such knowledge of the bore'sdepth. Conventional techniques used in the art are often inconvenient,time consuming and unreliable often requiring trial and error andmultiple exposures to radiographs before the proper implant insertion isachieved.

A common way to obtain the depth of the bore formed by a drilling toolis to use a depth gauge. Often users must interrupt the drillingprocedure in order to palpate or measure with a depth gauge whether ornot the desired depth has been achieved. In many instances a user willtake a radiograph during a drilling procedure to confirm the appropriatedepth of penetration has been achieved or take a radiograph while thedepth gauge is in place to ensure the information the gauge provides isaccurate. Depth gauges used in the art can be inaccurate resulting in auser placing a screw of an inappropriate length not often identifieduntil a confirming radiograph is taken. Each radiograph taken increasesthe radiation exposure of the surgeon, staff and patient in theoperating suite. Depth gauges known in the art can also break andrequire the user to retrieve it from the bore. Inconvenient andinaccurate depth measurement devices and methods can result inimproperly sized screws that must be removed and replaced with newproperly sized screws. Wasted hardware, increased disruptions and delaysin orthopedic procedures ultimately increase the expense of a procedureas well as expose the surgeon, staff and the patient to unnecessaryradiation. The cost of the additional time, the wasted hardware and theradiation exposure are quite significant.

SUMMARY

The techniques known in the art to drill holes in bone are technicallydemanding and require separate measuring steps that interrupt the actualdrilling of the bone adding time, cost and the need for additionalconfirming radiographs to complete such procedures. There remains a needfor safer, controlled drilling methods and devices. There is also a needfor an instrument that simultaneously controls and measures the depth ofpenetration of the instrument during procedures such as placement ofinternal fixation devices, screws, and other implantable hardware.

In one aspect, disclosed is a medical driving device including a housinghaving a proximal end and a distal end. The housing includes a hand-heldportion near the proximal end of the housing; and an engagement portionnear the distal end of the housing; a first drive shaft extendingthrough a region of the housing between the proximal and distal ends; afirst drive element coupled to a region of the first drive shaft; asecond drive element coupled to the first drive shaft and to a seconddrive shaft; a coupler coupled to the second drive element, the couplerinterchangeably connected to a working tool; and a tool guide assembly.The tool guide assembly includes a tool guide surrounding the workingtool; a forward surface guide having a proximal region and a distalregion, the distal region configured to couple to the tool guide; and arear surface guide configured to couple to the first drive shaft and theproximal region of the forward surface guide. The device furtherincludes a programmable electronics package configured to sense torquein at least the second drive element.

The first drive shaft and the second drive shaft can be in a co-axialarrangement, parallel arrangement, or an orthogonal co-axial arrangementrelative to one another. The hand-held portion further can include anactuator. The second drive element coupled to the second drive shaft candrive the coupler and the working tool. The coupler and the working toolcan be rotated by the second drive shaft. The coupler and the workingtool can be oscillated by the second drive shaft. The tool guideassembly can travel axially towards the proximal end of the housing to aretracted state upon actuation of the first drive shaft. Axial travel ofthe tool guide towards the proximal end of the housing can reveal alength of the working tool that extends beyond the tool guide. Theworking tool can be a drill bit, a detuned drill bit, wire, Kirschnerwire, pin, trochar, burr, screwdriver, reamer, saw, saw blade, router,router bit, stepped drill bit, bone plug removal tool, bone harvestingtool, bone marrow harvesting tool, and bone marrow aspirating tool. Theprogrammable electronics package can measure current used to drive thesecond drive element. The current measured can correspond to a torque ofthe working tool and the material strength and density of workpenetrated. The device can further include a torque sensor positioned onthe housing between the second drive element and the working tool, thetorque sensor configured to directly measure torque of the working tool.The torque sensor can be configured to communicate measurements oftorque to the programmable electronics package. A change in themeasurements of torque can correspond to change in material strength anddensity of work penetrated.

The device can further include an alert such that the torque sensorcommunicates with the programmable electronics package in real-time andthe alert provides a user with information regarding status of thedriving device during use. The alert can be an auditory, visual ortactile signal. The work penetrated can be medullary canal, cancellousbone, cortical bone, or soft tissue. The device can further include oneor more axial force sensors configured to sense the axial force appliedat one or both of the distal end of the tool guide and the working tool.The device can further include an axial force alert, the axial forcesensor communicates with the programmable electronics package inreal-time and the axial force alert provides a user with informationregarding status of the driving device during use. The axial force alertcan be an auditory, visual or tactile signal. The visual signal can beone or more LEDs positioned within a user line-of-sight, wherein theLEDs indicate degree of axial pressure being applied by the user inreal-time. The proximal region of the forward surface guide can betelescopically coupled to the rear surface guide. The device can furtherinclude a gearbox connecting the second drive element to the workingtool. The tool guide surrounding the working tool can be configured toassist in the engagement of an implant. The tool guide can include oneor more features that mechanically couple with corresponding features ofthe implant. The implant can be a fracture fixation plate or a jointpart. The tool guide can couple to the implant at an angle away fromperpendicular.

In another aspect, disclosed is a method of penetrating bone using adriving instrument including contacting a field of bone with a distalengagement end of the instrument; receiving a first input by a firstdrive element of the instrument, the first drive element coupled to aworking tool; driving the working tool at a first speed; receiving asecond input by a second drive element of the instrument, the seconddrive element coupled to a guide surrounding at least a portion of thedistal engagement end of the instrument; moving the guide axially in aproximal direction; and revealing a length of the working tool extendingbeyond the distal engagement end of the instrument.

The length of the working tool extending beyond the distal engagementend of the instrument can correspond to a depth of penetration by theworking tool into the field of bone. The method can further includereceiving commands by the instrument to electronically program the depthof penetration by the working tool. The method can further includeinstantaneously measuring axial motion of the guide using a transducercoupled to the instrument. The method can further include adjustingaxial movement of the guide to avoid plunge of the working tool. Themethod can further include adjusting movement of the working tool toavoid tissue damage. The method can further include alerting a user of achange in axial force against the field of bone using a signal, whereinthe signal comprises an auditory, visual or tactile signal. The methodcan further include instantaneously measuring torque of the workingtool. The torque can be measured electronically. The torque can bemeasured directly using a torque sensor in contact with at least aportion of the second drive element. The torque can correspond to amaterial strength and density of the field of bone. The method canfurther include alerting a user of a change in material strength anddensity of the field of bone using a signal, wherein the signalcomprises an auditory, visual or tactile signal. A change in torquemeasured can indicate a transition from a first tissue type to a secondtissue type. The first tissue type can include cortical bone and thesecond tissue type can include medullary canal or cancellous bone. Thefirst tissue type can include medullary canal or cancellous bone and thesecond tissue type can include cortical bone.

Other features and advantages will be apparent from the followingdescription of various embodiments, which illustrate, by way of example,the principles of the disclosed devices and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective, cut-away view of one embodiment of aninstrument.

FIG. 2 is a side, cut-away view of the instrument of FIG. 1.

FIG. 3 is a perspective view of another embodiment of an instrument.

FIG. 4 is a perspective view of the instrument of FIG. 3 showing alength of the working tool in an extended position.

FIG. 5 is an exploded view of the instrument of FIG. 3.

FIG. 6 is a perspective view of an instrument having a guide interfacedwith a fracture fixation plate.

FIG. 7 is a perspective view of the guide of FIG. 6 interfaced with thefracture fixation plate.

FIG. 8 is a perspective view of a guide/fixation plate interface system.

FIG. 9 is a perspective view of a guide coupled to the instrument ofFIG. 6 interfaced with the fracture fixation plate.

FIG. 10 is a side view of a drill bit having detuned flutes.

FIGS. 11A and 11B are perspective views of an instrument having a sawblade and saw blade guide coupled thereto.

FIG. 12 is a side view of an instrument having a driving tool coupledthereto.

FIG. 13 is a perspective view of another embodiment of an instrument.

FIG. 14 is a perspective view of a rotary encoder for use with aninstrument described herein.

FIG. 15 is a schematic view of a drive mechanism showing torque forcesgenerated by a working tool, gearbox and motor.

FIG. 16 is a schematic view of a direct torque sensor measuring forceproduced by drilling torque.

DETAILED DESCRIPTION

This disclosure relates to a surgical instrument for preparing a bore inanimal tissue. In an embodiment, the disclosure relates to a surgicalinstrument that drives a tool in which both drive power and relativeaxial extension of the tool are controlled and measurable. Theinstrument can have both a rotational drive and an axial drive, each ofwhich can be controllable by the user. The instrument allows a user tocontrol and simultaneously measure the travel of the tool into a targettissue.

FIGS. 1-2 illustrate cut-away views of an instrument 10. The instrument10 can include a body 20 that houses two drive motors 30, 60 and aworking tool 110 coupled via a chuck 90 extendable near a distalengagement end 120 of the instrument 10. As will be described in moredetail below, the instrument 10 can instantaneously sense, meter andcontrol the work created by the tool 110.

Instantaneous sensing, metering and controlling the instrument 10 helpto prevent injury to surrounding tissues and structures that couldotherwise be caused by the tool 110. For example, sensing, metering andcontrolling the rotational speed of the drive can reduce the risk ofheating surrounding tissue and bone, for example to the point of causinglocalized burns. Sensing, metering and controlling the axial motionand/or relative extension of the working tool 110 can preventpenetrating injuries, for example, to structures distal of the targetsuch as nerve, brain, spinal cord, artery, vein, muscle, fascia, bone orjoint space structures. Instantaneous sensing, metering and controllingthe bore created as the working tool penetrates the tissue can providean advantage when selecting implants for insertion. For example, thelength of the drilling hole and subsequently the length of the implantneeded can be simultaneously metered upon creating the bore. Thiseliminates the need for an additional step of measuring the depth of thebore created with a separate device. Further, depth gauges canfrequently provide false measurements resulting in users selecting thewrong size implant for insertion and requiring them to remove theimplant and reinsert a different sized implant. Conventional depthgauges are also prone to breakage, which can lead to additional timeusage and patient morbidity. Sensing, metering and controlling the depthof the bore in real-time or as it is being created eliminates thetrial-and-error process of selecting the correct implant for theprocedure, which ultimately can improve patient safety.

The instruments described herein also save operating time and the needfor additional procedures like repeated radiographs in determiningimplant size. Because estimates of operating room costs for thepersonnel alone can be as high as $25 per minute even small savings oftime in an operating room can result in large savings of money. Theinstruments described herein provide an added benefit of reducing thenumber of radiographs needed in the operating room. Intra-operativeradiographs and radiation exposure are one of the major occupationalrisks to surgeons and operating room staff. Radiation exposure of thistype has been shown to lead to radiation dermatitis, cataracts, skincancers, leukemia and other cancers. The instruments and methodsdescribed herein reduce the number of radiographs needed per procedureand the life-time exposure of surgeons and staff to x-rays. This reducedradiation exposure ultimately lowers chronic radiation exposure and therisk of radiation-related illnesses in surgeons and their staff.

Drive System

The configuration of the drive system of the instrument 10 can vary. Inan embodiment shown in FIGS. 1-2, drive motor 30 of the instrument 10can be a fixed axial drive motor 30 and drive motor 60 can be aslidable, rotational drive motor 60. Drive motor 30 can be coupled to adrive shaft 40, which can in turn be coupled to drive motor 60. Thedrive shaft 40 can be a jack screw, ball screw, lead screw and the likethat can translate the torque or rotary movement of the drive motor 30into thrust in an axial direction to slidably move the drive motor 60relative to the instrument 10. The drive shaft 40 can be made to moveeither in a distal (forward) direction or a proximal (reverse) directionthat is substantially parallel to the axis of the instrument 10. Thedrive motor 60 can connect to the drive shaft 40 by way of a detachablecoupler 50. The drive motor 60 can be coupled to and rotate a driveshaft 80 that can connect to the chuck 90 that holds the working tool110. As such, movement of the drive motor 60 along the longitudinal axisof the instrument 10 can cause similar movement of the working tool 110and extension of the tool 110, for example beyond the distal engagementend 120 of the instrument 10.

In use, the drive shaft 40 driven by drive motor 30 can axially drivethe drive motor 60, which can rotate the drive shaft 80, which canrotate the chuck 90 which can rotate the tool 110. The chuck 90 can bestabilized within the body 20, for example by bearings 100. The bearings100 can be axially slidable and stabilizing. The second drive motor 60can be constrained or held rotationally still to provide for theeventual rotational movement of the working tool 110. The drive motor 60can be fixed against rotational movement by guide rails or anti-rotationconducting flanges 70. In an embodiment, the flanges 70 slide withinchannels in the body 20. In an embodiment, each channel can have anopposite polarity such that they conduct electricity from a power sourceto the drive motor 60. In another embodiment, the power can be separatefrom the conducting flanges 70. The anti-rotation conduction flanges 70can also be spiral shaped and travel through spiral grooves to addstability. The anti-rotation conduction flanges can also be excludedfrom the device and the rotational drive motor fixed to the axial driveshaft 40 causing the drive motor 60 to turn along with the axial driveshaft 40.

It should be appreciated that the configuration of the drive shaft 40,80 relative to the drive motors 30, 60 can vary. For example, the motors30, 60 can be in parallel overlapping orientation relative to oneanother as shown in FIGS. 1 and 2. Alternatively, the drive shaft 40 andmotor 30 can be positioned in a co-axial orientation as shown in FIGS.3, 4 and 5. In another example, the drive shaft 40 and motor 30 can bepositioned orthogonal to drive shaft 80 and motor 60. For example, therotated motor can be positioned within the handle 25 of the instrument10. The parallel overlapping orientation as well as the orthogonalorientation can provide for a shorter, more compact length of theinstrument 10 without limiting the overall extension of the tool 110that can be achieved. Alternatively, the drive shaft 40, 80 and motor30, 60 can be connected via a gearbox (not shown).

It should also be appreciated that use of the term “working tool” hereinor “rotation of the working tool” is not intended to be limiting andthat working tools other than rotating drill bits are considered as willbe described in more detail below. Although the embodiments shown hereinuse motors, such as a stepper motor powered by a battery, it should beappreciated that power systems other than rotational drive motors areconsidered. For example, a non-electric drive motor, pneumatic motors oractuators powered for example by a nitrogen gas source, electricalmotors, hydraulic actuators, and the like or a combination thereof canbe incorporated into the instrument. It should also be appreciated thata motor and gearing can be used in place of the two-motor embodiment.

Instrument Guides

Extension of the working tool 110 relative to the longitudinal axis ofthe instrument 10 can be accomplished as described above via linearmovement of the drive motor 60 within the body 20 of the instrument 10.In another embodiment, the drive motor 60 need not move axially relativeto the instrument 10. Instead, extension of the working tool 110relative to the distal engagement end 120 of the instrument 10 can beeffected by the movement of one or more surface guides on the instrument10 as will be described below. FIGS. 3-5 illustrate an embodiment of aninstrument 10 that includes a body 20 that houses an axial drive motor30, a rotational drive motor 60, a working tool 110 coupled via a chuck90 extendable near a distal engagement end 120 of the instrument 10. Achuck extension 280 can also be included. The instrument 10 can furtherinclude a rear surface guide 300 and a forward surface 302 guide that,as will be discussed in more detail below, can be withdrawn in aproximal direction to reveal a length of the working tool 110 extendingbeyond the distal engagement end 120 of the instrument 10.

The drive motor 30 can be an axial drive motor and spindle seated nearthe proximal end (rear) of the body 20 and the second drive motor 60 canbe a rotational drive motor and spindle seated near the distal (front)end of the body 20. Body insert 220 can fit inside the top of the body20 such that the body insert 220 covers the drive motors 30, 60 (seeFIG. 5). The drive motor 30 can attach to drive a drive shaft 40 and thedrive shaft 40 can attach to the drive lug 240. The drive lug 240 canattach to the rear surface guide 300 at its proximal end. The distal endof the rear surface guide 300 can attach to the proximal end of theforward surface guide 302. There can be one or more o-rings 250 betweenthe two surface guides 300, 302. The drive lug 240 and the rear surfaceguide 300 can sit in the body 20 above the body insert 220. The top ofthe body 20 also can accept a body cover 214. The rear surface guide 300can fit between the body 20 and the body cover 214 such that it is freeto move within the body 20 and extend beyond the body 20 and the bodycover 214.

As best shown in FIG. 3, the forward surface guide 302 can engage anouter surface of the chuck 90, for example, via a sleeve and/or one ormore stabilizing flanges 305. In another embodiment, the chuck 90 canfunction without a sleeve or stabilizing flanges and instead the forwardsurface guide 302 can have a bushing or other device to engage the chuck90 directly and still allow the chuck 90 to spin freely.

In use, the axial drive motor 30 can power the drive lug 240 in an axialdirection, which in turn can drive in an axial direction the rearsurface guide 300 coupled to the forward surface guide 302. An increasedlength of the working tool 110 is revealed in order to engage the work.The drive motor 60 rotates the chuck 90 and the working tool 110.

The surface guides 300, 302 shown in the drawings have two “arms” orsupports that extend axially. But it should be appreciated that thesurface guides 300, 302 can have one, two, three or more arms thatprovide additional support to bear the load. It should also beappreciated that the surface guides 300, 302 can be a single unit. Inanother embodiment, the surface guides 300, 302 can be telescopingsurface guides. This can provide the instrument 10 with a larger rangein overall drill length in a more efficient configuration. Thetelescoping surface guides can each include an actuator such as apneumatic, hydraulic, motorized or other actuator that causes thesurface guides 300, 302 to telescope and change overall guide length(i.e. telescope outward to lengthen or telescope inward to shorten). Inanother embodiment, the telescoping surface guides 300, 302 can be usedto achieve depth control without the use of an axial motor. The axialelectric motor can be replaced by a hydraulic or pneumatic motor, as canthe rotational motor.

A distal guide 170 can optionally be coupled to the instrument 10. Inone embodiment, the distal guide 170 is coupled to a distal end of thebody 20 of the instrument 10 (as shown in FIGS. 1 and 2). In anotherembodiment, the distal guide 170 is coupled to the forward surface guide302 (as shown in FIGS. 3-5). The distal guide 170 can include a centralchannel through which the working tool 110 can extend to engage thework. The distal guide 170 can have a tapered geometry or reduced outerdiameter such that its contact surface is relatively small compared tothe distal end of the body 20 and the bulk of the instrument 10 isfocused into a small area of contact with the work. The distal guide 170can also include gripping features at its forward surface such as spikesor other protrusions such that the guide 170 can hold its position onthe work.

The distal guide 170 can assist in the engagement of bone, fractureplates or other implants or joint parts. One or more portions of thedistal guide 170 can couple with the implant, for example by directlypressing or screwing the implant onto one or more corresponding featuresof the distal guide 170. FIGS. 6-9 show an instrument and variousembodiments of distal guides 170 a, 170 b, 170 c that can interface withthe work using various mechanisms. Guide 170 a can engage an implant815, such as a fracture fixation plate, by a threaded interface, or byanother mechanism, such that the guide 170 a screws into, or otherwisecouples with the implant 815. Guides 170 a and 170 b are shown connectedto the implant 815 in a generally perpendicular configuration.Alternatively, distal guide 170 c can connect to the implant 815 at anangle away from perpendicular. The guide 170 b can include an interfacethat provides a unique connection with the implant 815. For example, thedistal guide 170 b can include a pin-index type connection or adiameter-index type system that provide non-interchangeable connectionsbetween the distal guide 170 and the implant 815. As such, a specificimplant 815 can interface with a particular distal guide 170 to preventmisconnections.

The specific geometry of the interface between the distal guide 170 andthe implant 815 can vary. FIG. 8 shows a schematic of just one exampleof an interface system between the implant 815 and the distal guide 170.The distal guide 170 can include one or more geometric features 805 thatextend from a forward surface of the distal guide 170. The geometricfeatures 805 can couple with corresponding geometric features 810provided on the implant 815 such that the two properly and uniquelyinterconnect. The corresponding geometric features 805, 810 can dictatethe type of implant 815 that can be used with a particular distal guide170 providing for a unique pairing between the two. It should beappreciated that although the figure shows the implant 815 as a fracturefixation plate, the implant 815 with which the guide 170 can interfacecan vary including bone, fracture plates or other implants or jointparts.

The interface between the distal guide 170 and the implant 815 canprovide for directional guidance for the working tool 110. The implant815 can connect to the distal guide 170, the distal guide 170 canconnect to the instrument 10 resulting in one interconnected complex fordrilling a bore. In one embodiment, the implant 815 couples to thedistal guide 170 which can be attached to the instrument 10 via theforward surface guide 302. The implant 815 can also couple a distalguide 170 that is separate from the instrument 10. In another embodimentshown in FIG. 9, the instrument can include two guides. In thisembodiment, a first distal guide 170 is attached to the instrument 10and a second distal guide 170 a is connected to the implant 815. Thefirst distal guide 170 can then couple to the second distal guide 170 a.

Working Tools

As mentioned above, the working tool 110 can be connected to theinstrument 10 using a rotatably-driven coupler or chuck 90 with orwithout a chuck extension 280. The chuck 90 can be a conventionalcoupler such as a three-jaw chuck in which the jaws grasp the proximalportion of the tool 110 and hold it firmly in place. The chuck 90 can beactuated to open or close the jaws by a rotation mechanism or a key orother techniques known in the art. The chuck 90 can also be aquick-release type of coupler. The chuck 90 can be extended beyond thedistal engagement end 120 such that the chuck 90 can be accessedexternal of the body 20. This accessibility of the chuck 90 relative tothe instrument 10 allows for a user to make reliable connections betweenthe working tool 110 and the chuck 90. The exterior access can alsoallow for shorter, safer driven tools than if the chuck 90 was internalto the instrument body 20. Additionally, the exterior access can providefor ease of cleaning this portion of the instrument 10.

The working tool 110 as described herein can include, but is not limitedto, tools such as a drill bit, Kirschner (or other) wire, pin, trochar,burr, screwdriver, reamer, saw, saw blade, router, router bit, steppeddrill bit, bone plug removal tools, bone harvesting tools, bone marrowharvesting tools, bone marrow aspirating tools or any other tools thatcan be reversibly attached to a chuck 90 or other type of couplingdevice. It should be appreciated that where a working tool is describedherein as a drill bit or wire or pin or other type of tool that suchdescription is not intended to be limiting. It should be appreciatedthat a wide variety of tools can be used as the working tool with theinstruments described herein. For example, the working tool can be a sawblade connected to a coupler that oscillates or reciprocates the sawblade as described with respect to FIGS. 11A-11B below or a wire driveras described with respect to FIG. 12 below.

The working tool 110 can be made of metal materials such as titaniummetal or stainless steel that can be sterilized and reused.Alternatively, the working tool 110 can be made of polymeric materialthat can be discarded after each use. The material can be chosen toprovide the necessary strength to allow the proper tool action.

FIG. 10 shows an embodiment of a drill bit 905 having a flute 910 thatis detuned or dulled. It should be appreciated that the entire length ofthe flute 910 need not have the same edge geometry. For example, thedetuned flute 910 can have an edge 915 that is sharper starting at aproximal region of the bit 905 towards the tool attachment region. Itshould also be appreciated that the bit 905 can have more than one flute910 as is known in the art. The detuned flute 910 allows for greatersensitivity in measurement of torque and measurement of current. The bit905 can also have fast spirals 920 with short rotational diameter and ashort tip 925 such that it transfers less energy to the work to avoidover-heating the work and surrounding tissues. The drill bit 905 designalso can provide a feel to the user such that information regarding thesubtle material strength and density changes of the work can beappreciated during use.

Other Tool Embodiments

It should be appreciated that other medical devices can incorporate themetering and controlling features of the instruments as describedherein. FIGS. 11A and 11B show an embodiment of an instrument 1005having a working tool that is an oscillating bone saw blade 1010 coupledto chuck 1090 and surrounded by a saw blade guide 1007 that is coupledto a forward surface guide 1002 coupled to a rear surface guide 1000.The oscillating saw blade 1010 can have opposed proximal and distal endsand can be formed so that teeth 1015 extend forward from the distal endof the planar body of the blade 1010. The arrangement and geometry ofthe teeth 1015 can vary. The body of the blade 1010 can be formed ofmaterial such as stainless steel or other appropriate cutting material.The teeth 1015 can extend forward from the blade distal end through anelongate slot 1008 in the saw blade guide 1007 coupled to the instrumentas best shown in FIG. 11B. The proximal end of the blade 1010 caninclude features (not shown) that facilitate the coupling of the blade1010 to a chuck 1090. The chuck 1090 can connect to a drive mechanismthat oscillates or reciprocates the saw blade 1010 to effect cutting.For example, the distal end of the blade 1010 can pivot back and forthrelative to the proximal end of the blade 1010. As the saw blade 1010saws through material, another drive mechanism can drive the rearsurface guide 1000, the forward surface guide 1002 and the saw bladeguide 1007 in an axial direction such that the body of the blade 1010extends further through the slot 1008 of the saw blade guide 1007. Theslot 1008 and the guides 1000, 1002, 1007 are configured such that theydo not interfere with the oscillating and/or reciprocating motion of theblade 1010. The length of the blade 1010 can vary to accommodate variousdepth penetrations.

FIG. 12 shows an embodiment of an instrument 1105 having a working toolused to implant a Kirschner wire (k-wire) or other wire or pin. In anembodiment, the instrument 1105 can incorporate a wire driver 1110 usedto implant a k-wire 1115 (or other wire or pin, hereinafter called“wire” for simplicity). The wire driver 1110 can be a modular attachmentthat can be used with the various instruments described herein. Forexample, the wire driver 1110 can be inserted into other instruments 10described herein and used in place of the chuck 90, which can beremovable. Alternatively, the wire driver instrument 1105 can becompletely separate embodiments in which the wire driver 1110 is notmodular or removable and instead is coupled permanently to theinstrument 1105. It should be appreciated that the various instrumentsdescribed herein can be modular such that mechanical features such asthe chuck 90 or the axial drive motor 30 can be swapped out in place forone another.

The wire driver 1110 can hold the wire 1115 as well as rotate oroscillate the wire 1115. The wire driver 1110 can be released to slideaxially to a new position causing more (or less) wire 1115 to be exposedfor allowing a further penetration of the bone. In an embodiment, thebody 1120 of the driver 1105 including the internal workings arecannulated such that the wire 1115 can be fed through the driver 1105body 1120. The wire 1115 can extend through the cannulation in the body1120 of the driver 1105 from the front of the driver 1105 out throughthe back end 1125 of the driver 1105. As mentioned, the wire driver 1110can hold the wire 1115 in place much like a drill chuck. When the wiredriver 1110 is activated, the rotational motor (not shown) can oscillateor rotate the wire 1115 in a clockwise or counter-clockwise direction.As with previous embodiments, the rotational motor can be biased ineither rotational direction.

When the driver 1105 is activated the axial drive (not shown) can pullthe surface guide(s) 1130 back (proximally) and the wire 1115 canadvance into the work site such as bone. A trigger 1135 can beincorporated into the driver 1105 that holds the wire 1115 when graspedby a user. If pressure on the trigger 1135 is released, the trigger 1135releases the wire 1115 such that the driver 1105 can slide forward orbackward to expose less or more wire 1115, respectively. When a userdesires more wire 1115, the trigger 1135 can be released and the driver1105 pushes the surface guide 1130 forward. The length the surface guide1130 moves forward equals the length of wire 1115 that is now availablefor advancement into the bone. This length can be added to the computedtotal axial distance as needed to obtain an accurate account of thelength of wire 1115 that was driven into the bone. The wire 1115 can beheld in place by either the guide 1130 (such as by pinching) or the boneinto which the wire 1115 was driven can itself be used to hold the wire1115 in place. If the wire 1115 is held in place by the bone, the usercan urge the guide 1130 against the bone as the surface guide 1130pushes the driver 1105 back to let out more wire 1115. If the userdesires to remove the wire 1115 from the bone, the reverse axial drive(not shown) can be engaged such that the surface guide 1130 move forwardand the driver 1105 moves backward away from patient while the trigger1135 is engaged. It should also be appreciated that, although not shown,this instrument embodiment can incorporate a distal guide 170 coupled toa forward end of the surface guide 1130 as described in previousembodiments.

Tool Actuation

Actuation of the drive motors and other features of the instrumentsdescribed herein can vary. Actuators can include triggers, buttons andswitches that can be retracted, pressed, squeezed, slid or otherwiseactuated to perform a certain function of the instrument 10. Theactuators can be incorporated into a handle of the instrument 10 in sucha way that is ergonomically comfortable for a user. For example, theinstrument can include a pistol grip having trigger-type actuators suchthat the instrument 10 can be easily and comfortably held and actuatedduring use. It should be appreciated, however, that the instrument 10can have other configurations such as a straight-bodied instruments thatdo not include a pistol grip.

Each drive motor can have a separate actuator for activation. Forexample, the drive motor 30 can be turned on by actuator 32 and thedrive motor 60 can be turned on by actuator 62 (see FIG. 1). Theactuators 32, 62 can be depressible triggers positioned on a handle 25of the body 20, such as within a trigger housing 212. The actuators 32,62 can adjust the speed of the drive motors 30, 60 in a manner that isproportional to the degree of depression of the actuators 32, 62, forexample relative to the instrument handle 25. The direction the driveshaft 40 moves can be changed from a forward to a reverse direction, forexample, by the position of a switch or other selectable mechanism.Similarly, the drive motor 60 can be made to move in a forward orreverse direction as determined by the position of a selectable switch.Further, the motor can be biased in either rotational direction.

In another embodiment shown in FIGS. 3-5, the instrument 10 can includea forward trigger 232 and a reverse trigger 234 that can each actuateboth drive motors 30, 60. The forward trigger 232 can be a two-stageforward trigger 232 such that it can engage the rotational drive motor60 in the first stage (i.e. effecting working tool 110 rotation) and theaxial drive motor 30 in the second stage (i.e. effecting working tool110 extension). The speed of the rotational drive motor 60 can beproportional to the degree of actuation of the first stage of theforward trigger 232, for example depression of the trigger 232. Thespeed of the axial drive motor 30 can be proportional to the degree ofactuation of the second stage of the forward trigger 232. In anembodiment, the trigger 232 in the first stage can engage the rotationaldrive motor 60. The tool 110 spins and with further depression of thetrigger 232 can reach full speed. Just before the trigger 232 enters thesecond stage, the axial drive motor 30 can engage. The axial drive motor30 can cause withdrawal of the surface guides 300, 302 in a proximaldirection P (see FIG. 4) to reveal a length of the working tool 110allowing it to engage with and bore into the work as the user appliespressure to the instrument 10 and keeps it engaged with the work. Itshould be appreciated that the axial drive motor 30 can also cause themovement of the working tool 110 in a distal direction to reveal thelength as described with respect to other embodiments herein. It shouldbe appreciated that an axial force sensor can be incorporated thatassists a user in keeping the instrument engaged with the work, as willbe discussed in more detail below.

The reverse trigger 234 can cause both of the drive motors 30, 60 toreverse their direction. When the reverse trigger 234 is engaged whilethe two-stage trigger 232 is actuated during the first stage, therotational drive motor 60 as well as the chuck 90 and the working tool110, can spin in a reverse direction. When the second stage of theforward trigger 232 is actuated, and the reverse trigger 234 is stillengaged, the rotational drive motor 60 as well as the chuck 90 and theworking tool 110, can spin at maximal speed in a reverse direction andthe axial drive motor 30 can begin to spin proportional to the degree ofactuation of the second stage of the forward trigger 232. The action ofthe axial drive motor 30 can cause the drive lug 240, the rear surfaceguide 300, the forward surface guide 302 and the guide 170 to move inthe distal direction (i.e. towards the work in direction of Arrow D, seeFIG. 3). The axial movement of the guides 300, 302 can push theinstrument 10 away from the work and draw the working tool 110 out ofthe work. In another embodiment, the motors 30, 60 can have independentreverse functions and can be controlled independently via independentactuators or triggers.

The instrument 10 can also include an oscillation select switch 262 (seeFIGS. 3-5). The oscillating function can also be actuated by certaintrigger combinations or an oscillation trigger. When the oscillationselect switch 262 is in the “off” position, the instrument 10 canfunction as described above. When the oscillation select switch 262 isin the “on” position, the rotational drive motor 60 can oscillate in theappropriate direction when the triggers 232, 234 are actuated and theaxial drive motor 30 function is not affected. If the forward trigger232 is actuated, the instrument 10 can oscillate in the forwarddirection, i.e. the rotational drive motor 60 can oscillate forward butthe axial drive motor 30 can cause the drive lug 240, the rear surfaceguide 300 the forward surface guide 302 and the guide 170 to move in aproximal direction as before. If the reverse and forward triggers 232,234 are actuated, the instrument 10 can oscillate in the reversedirection, i.e. the rotational drive motor 60 oscillates in reverse butthe axial drive motor 30 can cause the drive lug 240, the rear surfaceguide 300, the forward surface guide 302 and the guide 170 to move inthe distal direction as before. The oscillation select switch 262 canaffect the function of the rotational motor 60 not the axial drive motor30. When selected it can cause the rotational motor 60 to oscillate.

Irrigation System

The instruments described herein can include an irrigation system. Theirrigation system allows for the surgical field to be kept cool whilethe instrument 10 is in use and reduce the risk of tissue damage such asbone burning and bone death. The irrigation system can also reduce therisk of hardware failure, the need for re-operation, infection, limbloss and death. The irrigation system can include one or more irrigationnozzles 130 located at or near the engagement end 120 of the body 20. Inone embodiment, the irrigation nozzles 130 spray fluid from the distaltip of the body 20. In another embodiment, the irrigation nozzles 130can be routed internally through the working tool 110. The irrigationfluid can be sprayed through a channel running through the working tool110 and exiting at a port near the distal end of the tool 110. In afurther embodiment, the forward surface guide 302 can have one or moreirrigation nozzles 130 (see FIGS. 3-5). The irrigation nozzles 130 canalso be coupled to the distal guide 170.

The irrigation nozzles 130 can deliver irrigation fluid (i.e. a liquidor a gas) through irrigation tubing 340 (see FIGS. 3-5) from a sterilefluid bag or other irrigation fluid source. In an embodiment, carbondioxide gas can be used to irrigate the work to remove heat. Theirrigation tubing 340 can be coupled to the instrument 10 via anirrigation port near a proximal end of the body 20. The irrigationtubing 340 can be angled downward to avoid crimping and for moreefficient manipulation of the instrument 10 by the user. An externalfluid pump or gravity can be used to pressurize the irrigation system.The irrigation system can be kept outside the sterile surgical fieldexcept, for example, the irrigation tubing 340 connected to theinstrument 10. Such an arrangement can contribute to the engagement end120 and the working tool 110 remaining relatively free from bulk orother awkward equipment enabling more accurate placement and easy use ofthe instrument 10 in the surgical field. The irrigation system of theinstrument 10 can also include a suction mechanism at or near thesurgical field. Suction can be applied through the irrigation nozzles130 or can be applied through additional channels.

The irrigation system can be controlled manually by the user such aswith an irrigation actuator positioned, for example, on a handle 25 ofthe instrument 10 or by a foot pedal or other mechanism. The irrigationactuator can be a depressible trigger or button that can turn on or offthe flow of irrigation fluid from the irrigation tube 340. The sameactuator or another actuator can turn on or off the suction applied tothe surgical field. The irrigation system can also be controlledautomatically for example by one or more sensors near the work sitecommunicating with an electronics package of the instrument to bedescribed in more detail below. Automated irrigation is generally adesired option for users as it can effectively reduce drill bittemperature, bone temperature and the risk of bone burning.

Modularity and Internal Access

The body 20 of the instruments 10 described herein can include one ormore removable covers that can be used to access one or more of thevarious internal components. Further, one or more of the internalcomponents can be modular and can be completely separated from the body20 of the instrument 10. This allows for interchanging parts as well ascleaning and sterilizing the components of the instrument 10.

In one embodiment, the instrument 10 can have a cover 122 near theengagement end 120 that can be removed to access, clean or remove thecoupler 90, bearings 100 and drive shaft 80 and any other internalcomponents of the instrument 10. The drive motor 60 can extend to aregion near the distal end of the body 20 and allow for the actuationand release of the coupler 50. For example, the release can be adepressible button 52 (see FIG. 5) on a surface of the drive motor 60that can allow a user to disconnect the drive motor 60 from the driveshaft 40 when the release is depressed to allow a user to remove thedrive motor 60 from the body 20.

In another embodiment shown in FIG. 13, a body cover 1515 can enclosethe rear surface guide (not shown) and at least a proximal portion ofthe forward surface guide 302. The forward surface guide 302 can becovered by the body cover 1515 up to the point where the chuck 90 isexposed at the distal engagement end 120 of the instrument 10 and canexit the body cover 1515 through openings 1520. These openings caninclude bushings seated around the perimeter of the opening 1520 thatare sealed from the remainder of the instrument body.

The one or more body covers 1515 can be removed independently of one ormore of the guides. Alternatively, the one or more body covers 1515 canbe integrated with one or more of the guides such that they can beremoved along with the covers 1515 in order to access the interior ofthe instrument 10. Proximally, the body 20 can include a removable endpiece 150 that can be removed to gain access to the proximal region ofthe body 20 in order to clean or remove the modular portions of theinstrument 10 near the proximal end, such as the drive shaft 40 and thedrive motor 30. The removable end piece 150 can be incorporated with aremovable electronics package as will be discussed in more detail below.One or more of the body covers can be translucent or transparent suchthat the components inside are visible from the outside without removalof the covers. It should also be appreciated that the components can bedisposable and need not be removed or cleaned.

Electronics and Sensors

An electronics package 236 can be positioned within the body 20 of theinstrument 10 and can have a variety of configurations. In anembodiment, the electronics package 236 can be positioned within thebody 20 as well as within the handle 25. In an embodiment, theelectronics package 236 can be positioned within a space of the body 20,for example near or at the proximal end behind drive motor 30 (see forexample, FIG. 5 or 6). The electronics package 236 can include adisplay. The electronics package 236 and display can be removable alongwith one or more of the body covers. Information regarding the use ofthe instrument 10 can be relayed in real-time to the display such thatthe information is provided to a user instantaneously during use of theinstrument 10, for example bore depth or other information as will bedescribed in more detail below. The display can include an LED or otherdisplay using, for example, electrical filaments, plasma, gas or thelike. The instrument 10 can also include a display that is not coupledor integrated within the instrument itself, for example, a heads-updisplay that communicates with the instrument 10 (i.e. either wired orwirelessly). The heads-up display can include a graphical user interface(GUI) that can display data and provide interactive functions such as atouch screen for input of data and information such as the drill bitsize. The heads-up display can be mounted as is known in the art such aswith a boom or other mechanism that provides user convenience. Forexample, the heads-up display can be mounted on a boom that can beeasily positioned and moved around during a surgical procedure. Theheads-up display can be autoclavable such that the display can bepositioned within the surgical field where a user is using theinstrument 10. Alternatively, the heads-up display can be inserted intoa sterile cover such that the display can be positioned within thesurgical field where a user is using the instrument 10.

The electronics package 236 (see FIGS. 5-6) can communicate with varioussensors positioned within the instrument 10 that assess the status ofthe components of the instrument and communicate this information inreal-time to the electronics package 236 and the user via a display. Theinstrument 10 can provide the user with alerts and information regardingthe status of the instrument and instrument components during use suchthat manual and/or automatic adjustments can be made. The electronicspackage 236 can also include motor control electronics and softwareprograms that can be programmed to automatically adjust the instrument10 in real-time to maintain use of the instrument 10 within setthresholds. For example, the instrument can include software capable ofbeing programmed to continuously measure and/or control a variety offunctions including, but not limited to, bone depth, material strength,bone density, skive, drill bit development, speed of rotation,acceleration, deceleration, irrigation, voltage, torque, thrust, feedrate, current, voltage, axial movement, axial force and other functionsof the instrument or a combination thereof. The instrument can includemechanical measurement systems, such as a mechanical torque measurementsystem as will be described in more detail below.

As such, the instruments described herein can detect and controlpenetration of the working tool through various tissue layers. Theinstruments can control, for example, axial feed rate, motor RPM, andengagement of the work to allow a user to avoid certain unsafeinstrument situations. For example, the instruments described herein candetect joint penetration in real-time allowing a user to avoid “popthrough” or plunging situations, for example, in which the instrumentsuddenly penetrates the cortical bone and inadvertently damages softtissue or joint structures. Joint penetration can occur perpendicularlyas well as tangentially (also known as skiving). The instrumentsdescribed herein can provide an overall system stability that allows forthe accurate tracking and detection and control of instrument statusduring use.

It should be appreciated that the control of the instruments describedherein can also be adjusted manually by the user. For example, the usercan change the thrust of the drive motor 30 by letting up or pressingdown on the actuator 32. The user can also change the thrust of theinstrument 10 by pushing down or letting up on the axial pressure beingapplied to the instrument 10. In an embodiment, tissue resistance ascompared to axial pressure on the instrument 10 applied by the user cancause/allow the relative position of the handle of the instrument 10 tofeel as if it were backing out of the work as the tool 110 is axiallyextended from the instrument 10. This can require the user to applyadditional axial pressure to drive the tool 110 through the tissue. Thetorque as related to the rotating tool 110 can also change during use ofthe instrument 10. This change provides feedback to the user who in turncan make appropriate adjustments to the axial and rotational movementsas needed.

The instruments 10 described herein can instantaneously measure theaxial motion and the depth the working tool 110 travels into the work bya transducer or encoder, such as an incremental rotary encoder, anabsolute rotary encoder, mechanical, magnetic, electrical, or opticalrotary encoder, or the like (see for example BEI Optical encoder;www.motion-control-info.com/encoder_design_guide.html). The depth theworking tool 110 travels into the work can also be measured by asynchro, a resolver, a rotary variable differential transformer (RVDT)or a rotary potentiometer, or the like. As shown in FIG. 14, the rotaryencoder 39 can include a bearing housing assembly 201, a light source202, a code disc 203, a mask 204, a photodetector assembly 205, anelectronics board 206 that rotate around shaft 208. In an embodiment,the rotary encoder is an incremental rotary encoder with dual channelsin quadrature with an additional data track to provide an internalposition reference for setting a “zero point”. The rotary encoder can bean absolute rotary encoder.

The encoder can measure rotation and convert that information into axialmotion. The encoder can interface with the drive motor 30 and the driveshaft 40 and can provide instantaneous information on the position ofthe drive shaft 40 regarding the depth of axial movement of the workingtool into a bore. This information can be fed to the electronics package236 that can perform count multiplication to determine the toolposition. For example, the rotation of the drive shaft 40 can be measureand a calculation performed to determine the distance traveled. Thisdistance traveled can be compared to a set point or zero point such thatthe position of the working tool 110 from the distal end of theinstrument can be calculated. This calculation relates to depth asdetermined by the position of the distal end of the instrument withrespect to the target tissue (e.g. bone).

In an embodiment, the instrument can include a meter that measures therotational speed (see for example the speed device described in U.S.Pat. No. 4,723,911), time, velocity, acceleration, deceleration ortorque. The meter can provide the user information pertaining to thepassage of the working tool 110 through different layers of tissue. Forexample, movement of the working tool 110 through cortical bone intomedullary canal or cancellous bone, medullary canal or cancellous boneto cortical bone, or from cortical bone to soft tissue. In anembodiment, metrics can be obtained via an axial force sensor and/or atorque sensor to measure drive or motor torque directly. In anembodiment, the rotational drive motor 60, or a gearbox connected to therotational motor 60, can be positioned such that it can press against aforce sensor to provide direct measurements of torque that can bedisplayed to a user and provide information pertaining to the passage ofthe tool through varied layers of tissue.

In another embodiment the rotational drive motor 60 can have a torquesensor (not shown). In an embodiment the rotation drive motor 60 can bea brushless DC (BLDC) electric motor having one or more Hall sensors.When the tool passes from cortical bone into medullary canal orcancellous bone or from cortical bone into soft tissue the measuredtorque can drop dramatically. The information can be relayed to thedisplay 236 and integrated with the function of the motor drivers andtheir actuators. For example, in an embodiment, when the tool 110 ismoving axially in a forward direction and passes from cortical bone tomedullary canal or cancellous bone or from cortical bone to soft tissuethe reduced torque will interrupt the axial motion. The axial drive canthen be reengaged by releasing pressure on the forward two-stage triggerand reapplying pressure.

The instruments 10 described herein can also control the depth ofpenetration of the working tool 110. In an embodiment, the maximum depthof the bore that is to be created by the instrument 10 can be programmedwith electronics in advance of drilling. The measurement can be zeroedby the user prior to use, for example, by depressing an axialmeasurement selector/reset button. This allows the user to zero themeasurement according to the length of the selected tool 110. In oneembodiment, the distal end of the working tool 110 can be aligned withthe distal end of the body 20 and the instrument zeroed. This can beperformed manually by the user or electronically with set points and afeedback system (i.e. interface with the coupler). The alignment of thedistal end of the tool 110 and the distal end of the body 20 can be suchthat the two are flush with one another or the distal end of the tool110 can be some distance beyond the distal end of the body 20, forexample between about 3 mm and 7 mm. The tool 110 can be positionedflush against the bone prior to drilling. As the tool 110 advances intothe bone, the instrument 10 can be held flush against the bone. Theinstrument 10 can also include a distal guide 170 and be zeroed once thetool 110 aligns with the distal end of the guide 170 (and a fixationplate attached to the guide 170, if present). Once the cut is startedand the tool 110 can be flush with the bone, the user can use the axialdrive to further advance the tool 110 through the bone. The electronicspackage 236 can be zeroed as described above to include the additionalaxial length of the guide 170.

In another embodiment, the user can feed in a distal direction a portionof the working tool 110, for example 30 mm if working on a tibia orfemur or 12 mm if working on a radius. The user can then manually drillthrough the bone as with an axially static drill. Upon reaching thatpre-programmed depth, if the distal cortex had not yet been breached,the axial drive can be used to penetrate the bone further. In anotherembodiment, the electronics can contain a preset maximum distance thatcan limit the distal travel of the tool 110. For example, a stop and gosignal (i.e. single click of the trigger) or a double stop and go (i.e.double click of the trigger) can release the depth stop and allowfurther travel. Any of a variety of schedules can be programmed into theelectronics to control distal advancement of the tool. For example, eachtime the tool 110 is advanced beyond the initial stop, the electronicscan be programmed to allow only a further distal travel of for example 3mm or 6 mm or other incremental distance before stopping again andalerting the user similar to a snooze alarm system of a clock radio.

Identifying the desired depth of penetration for pre-programmedembodiments can be determined, for example, by knowing the typical sizeof the target tissue based upon the age and size of a patient or theactual size of the target tissue from pre-op radiographs, CT scans orMRI scans. A user can also manually estimate to approximately 70-80%depth travel through the proximal cortex, the medullar bone and close toor into the distal cortex prior to the automatic pre-programmed settingstaking effect. For example, the user can manually estimate until aregion of the bone is entered where a greater amount of control isdesirable such as the distal cortex. At that stage, the axial drive ofthe instrument can be used to slowly proceed through that portion of thebone to the target location. A user can also proceed until a pop is feltor a change in speed can be heard in the drill. This can be augmented byacceleration or torque measurements provided to the user. For example,as the drill bit penetrates to the very last layers of the distal cortexit can begin to accelerate with a burst of acceleration as it breechesthe distal cortex completely, this can also be sensed as a change intorque. In another embodiment, the RPM of the rotational drill motor iskept constant, preventing tool acceleration or deceleration. This allowsthe torque to be correlated to material strength. The instrument canprovide its own auditory output to accentuate the sometimes subtleauditory changes caused by the drill bit. Upon reaching thepredetermined target depth, axial movement of the device canautomatically slow or stop while rotational movement can continue. Itshould be appreciated, however, that the user can manually override anypre-programmed limitations or automated controls by actuation/triggerson the device without changing hand positions to continue.

As described above, the instruments described herein can include one ormore sensors that communicate information to the user using a variety ofalert mechanisms and/or graphical displays. In an embodiment, theinstrument includes an axial force sensor and an axial force alert. Asdescribed herein, the axial force sensor can be used to sense the axialforce applied at the distal end of the drill guide and/or applied by theworking tool. The axial force sensor can communicate with the axialforce alert and provide information to the user to ensure that thedistal end of the drill guide and/or tool stay engaged with the work andmaintains an appropriate level of pressure. Applying too much pressureor force on the work can increase the risk for damage to the work orsurrounding tissues. Applying too little pressure or force can cause thetool to back off the work and prevent tool advancement at the desiredrate. The axial force sensor can communicate with the axial force alertin real-time to provide the user with information regarding the statusof the drill guide and whether the applied axial force is at thedesirable pressure for an optimum result. The axial force alert caninclude an alarm or other auditory signal, a light or other visualsignal, a vibration or other tactile signal, or a combination thereof.In an embodiment, the visual output can be an LED light or graphicalinterface positioned in the line of sight with the work, for examplenear or at the proximal end or back of the device. The output of theaxial force alert can be proportional to the axial force being applied.For example, the axial force alert can include a light that can changecolor or a plurality of lights that sequentially illuminate depending onthe axial force applied. Alternatively, the axial force alert caninclude an auditory alert that changes pitch or frequency depending onthe axial force applied.

In use, the user can inadvertently lighten manually applied forward (oraxial) pressure on the instrument 10 that can result in a slowing ofprogress into the work and consequently the drill guide from backingaway from the work. A user can maintain forward pressure on theinstrument 10 such that the working tool 110 drives into the bonedistally as the guides retract in a proximal direction. If a user doesnot maintain forward pressure the instrument 10 can be pushed in aproximal direction resulting in the working tool 110 not moving into thework. It can be desirable, however, to use as little forward pressure onthe instrument as necessary to avoid injury to the bone. In someembodiments, the instrument 10 can include an axial force sensor thatcan measure the axial force a user applies to the work. The axial forcesensor can interact with the electronics and provide an output to theuser (e.g. visual or auditory or other output) to indicate when anamount of pressure is being applied by the user. The instrument can beprogrammed to provide the output to the user when an appropriate amountof pressure is being applied or when the pressure being applied fallsoutside a programmed range. In one example, LED lights can be positionednear a proximal end of the instrument within a user's line-of-sight suchthat the axial force applied can be visualized. For example, a flashingwhite LED can mean too little axial pressure is being applied, a greenLED can mean the axial pressure is in a desired range and a flashing redLED can mean the axial pressure is too high.

The instruments described herein can also include a torque sensor thatdetects the torque applied by the rotational motor and a torque alert.As described previously in reference to the axial force alert, thetorque alert can also include an alarm or other auditory signal, a lightor other visual signal, a vibration or other tactile signal, or acombination thereof. For example, the sensed torque similar to thesensed axial force can be displayed visually such as on a graphicalinterface in the line of sight with the work. The torque alert can alsobe proportional relative to the torque being applied. Further, theoutput for the axial force alert can be distinguishable from the outputfor the torque alert. For example, a first auditory signal can beprovided by the axial force alert proportional to the axial force and asecond auditory signal can be provided by the torque alert proportionalto the torque applied. The auditory signals from the two alerts can bedistinguishable by the user as being separate. For example, the axialforce alert can be a different pitched auditory signal compared to thetorque alert. In another embodiment, the axial force alert can signalthe user only when conditions at the work change, whereas the torquealert can be a continuous signal, such as a sound with a variable pitchthat is proportional to the torque or energy being sensed. It should beappreciated that any number of sensors and a variety of alerts orgraphical information can be used singly or in combination as is knownin the art.

The systems described herein can also provide information to the userregarding optimal screw placement even in the case of a shared orconvergent drill hole for the placement of interference screws, such asscrews that are purposefully touching. Clinically, a user can feel whenan interference screw is contacted by a drilling or driving device.However, once the interference screw is engaged the distal cortex can nolonger be clinically felt by the user and a myriad of potential problemsexist with regard to injury of distal structures. Both the interferencescrew and the distal cortex can be detected by tracking changes in themetrics, for example current or measured torque. The data can be used toinform the user in real-time when the instrument is in contact with oneor more of the bone cortices or the screw. Similarly, the instrumentsdescribed herein can provide instant, intra-operative feedback on drillbit performance such as drill flute clogging and the assessment of drillbit sharpness using a calibration block.

Material strength and bone density can be determined by comparingintraoperative metrics such as current, measured torque or axial forcewith existing empirical data obtained while drilling with known drillbit sizes, drill bit types, axial feed rates and motor RPMs. Theinstruments described herein therefore can be useful in diagnosing bonepathologies such as osteoporosis and the detection of holes or fracturesin the bone being drilled. Further, material strength and bone densitydata can assist a user in choosing an appropriate fixation technique,e.g. non-locking (cortical or cancellous) versus locking (unicortical orbicortical). Conventionally, to select the appropriate fixationtechnique a user must make an educated guess or using bone density dataobtained prior to the fracture to estimate local material strength atthe fracture fixation site. For example, dual energy X-rayabsorptiometry (DEXA) scans are commonly used to measure bone densityand monitor osteopenia or osteoporosis treatments. But a DEXA scancannot be performed acutely for a fracture patient and the standardizedregional measurements may not be relevant at the fracture site. Theinstruments described herein provide an advantage in that determinationof bone strength and bone density can be performed in acute situationsand in real-time at the fracture site.

Drilling torque (or energy) of the working tool is related to theproperties of the bone, such as its material strength and its bonedensity. One or more of the sensors described herein can be used toestimate the material strength and bone density such that the instrumentcan detect transitions between different types of bone, as well as entryand exit from bone in real-time.

As shown in FIG. 15, a motor 60 can rotate and produce a motor torqueT_(m) that is in the direction of rotation of a working tool 110 coupledto the motor 60. Drilling torque T_(d) is opposite the direction ofrotation of the working tool 110. A gearbox 75 can be incorporated inthe instrument to convert the high-speed, low-torque operation of themotor 60 to a higher torque working tool 110 speed. The gearbox 75 canexhibit an additional torque component T_(g) due to internal energylosses, such as mechanical losses in the form of drag that counteractstorque and can result in a loss of energy between the motor 60 and theworking tool 110. Gearbox torque T_(g) is also opposite the direction ofrotation of the working tool 110. The motor 60 can be held as thereference point and the motor torque T_(m) measured electronically. Inthis embodiment, the instrument measures the current required to operatethe motor 60, for example a brushless DC motor with a Hall Sensor thatoperates a drive train, and the motor 60 acts as both the actuator andthe sensor. Motor torque measurements in this embodiment include bothdrilling torque T_(d) and gearbox T_(g) losses. The gearboxinefficiencies can affect the accuracy of the torque measurements. Theerror in estimating the drilling torque component can be more pronouncedfor larger gear ratios in that more gears have more surface contact andthus, more drag.

In another embodiment, the instrument can directly measure torque (seeFIG. 16). The gearbox 75 is held as a reference point for the torquemeasurement and only the drilling torque T_(d) is measured. Measurementsof the drilling torque T_(d) can be taken at the output of the gearbox75 such that internal gearbox losses are not included in the torquemeasurement although the motor 60 may still drive against the internaldrag. A discrete sensor can be incorporated in the instrument to convertthe drilling torque T_(d) into a measurement signal. A mechanical beamor level can be incorporated to support the gearbox 75 and convert thetorque T_(d) into a linear force. The linear force can be converted intoan electrical signal using a strain gauge load cell or scale or othertorque sensor 77 to measure the resulting linear force. The directtorque measurement does not measure the energy lost internally to thegearbox 75 or the other motor components. The motor 60 can exert torquebetween its shaft and housing, which can be rigid mounted to the gearbox75. In this embodiment, the torque required to overcome the internallosses of the gearbox 75 can be transferred through the housing of themotor 60 and gearbox 75 and the mechanical path does not include atorque sensor. The torque sensor 77 can, instead be positioned betweenthe gearbox housing 75 and the working tool 110 by attaching the torquesensor 77 to the drill housing. The user can hold the body 20 of theinstrument 10, which is rigidly attached to the gearbox housing 75.

Although motor self-torque measurement can be more convenient since noadditional sensor is needed, the accuracy can be lower than for a directtorque measurement in which a torque sensor is used. Direct torquemeasurements from a manufacturing standpoint can also allow one todesign the gearbox independently from the torque measurementsensitivity.

The instrument 10 can be a corded or cordless powered instrument. In anembodiment, the instrument 10 includes and is powered by a removablebattery 360 (see FIG. 5). The battery 360 can be enclosed within abattery cover 362 capped on the bottom by a battery case cover 364. Thebody 20 can accept battery release buttons 366. The battery 360 can havedifferent chemical compositions or characteristics. For instance,batteries can include lead-acid, nickel cadmium, nickel metal hydride,silver-oxide, mercury oxide, lithium ion, lithium ion polymer, or otherlithium chemistries. The instruments can also include rechargeablebatteries using either a DC power-port, induction, solar cells or thelike for recharging. Power systems known in the art for powering medicaldevices for use in the operating room are to be considered herein.

Methods of Use

Below is an example of a method of using an instrument described herein.It should be appreciated that a variety of driving devices or workingtools can be coupled to the instruments described herein. Descriptionrelated to guides on a drilling device having a drill bit coupledthereto is not intended to be limited to only drills and drilling bores.Rather, the instruments and guides can be used to saw or drive intotissues as described herein.

It should be appreciated that any of the instruments described hereincan be coupled to robotic arms or robotic systems or othercomputer-assisted surgical systems in which the user uses a computerconsole to manipulate the controls of the instrument. The computer cantranslate the user's movements and actuation of the controls to be thencarried out on the patient by the robotic arm. Robotics can providereal-time pre- and inter-operative tactile and/or auditory feedbackalong with visualization, such as three-dimensional modeling. Therobotic system can have an articulated endowrist at the end of two ormore “working” arms configured to be inserted through a small portal. Astable, camera arm with two lenses (allowing stereoscopic images) can bealso inserted through another small portal. The end-effectors canmanipulate instruments and can have various degrees of freedom. The usercan control the robot through a console placed in the operating room,allowing control of both the external and internal surgicalenvironments. The user's interface can have instrument controllers thatcan filter tremor and decrease the scale of motion. Foot pedals canexpand the user's repertoire, allowing tissue coagulation andirrigation. Visual feedback can be through a stereoscopic display.Robotic systems to which the devices disclosed herein can be coupledinclude the Haptic Guidance System or RIO® Systems (MAKO Surgical Corp,Ft. Lauderdale, Fla.) and the da Vinci® Surgical Systems (IntuitiveSurgical, Sunnyvale, Calif.). Other surgical robots can be considered aswell including the Robot-Assisted Micro-Surgery (RAMS) system(MicroDexterity Systems, Inc.), NeuroArm® (University of Calgary), Zeus®Surgical robots, SpineAssist (Mazor Surgical Technologies, Israel),ROBODOC and ORTHODOC (Curexo Technology Corp., Fremont, Calif.), ACROBOT(Acrobot, Elstree, UK), PathFinder (Prosurgics Ltd., Loudwater, HighWycombe, UK), and Laprotek system (Hansen Medical, Inc.). Other roboticarms can be used with the instruments described herein such that theinstrument can be independently controlled by the robot as opposed todirect manipulation by the user.

In one embodiment of the method, the user can dissect tissue down to thebone and create a field large enough to put against the bone the workingtool 110 or distal guide 170 or an implant attached to the distal guide170. Screws can be placed across fractures without any other implants ora plate can be fixed across the fracture by bone screws. The screws canlock into the plate and bone. When a plate is to be used, the user cancreate a field large enough to place the plate. Alternatively, the platecan be inserted through a small incision such that the user can slide italong the surface of the bone in combination of blunt dissection of thetissue along the way (i.e. subcutaneous plate). The screws can beplaced, for example using a radiograph to find the holes in the plate,through small incisions through the skin with dissection down to thebone. The surrounding tissue can be protected using retractors, a guidethrough which the working tool is inserted, attachable guides placed onthe instrument and the like. If a distal guide 170 is used, the lengthof the guide 170 can be accounted for in the depth measurement. If aguide 170 attached to an implant is used, the depth can be automaticallyor manually zeroed. For example, if a plate is used the thickness of theplate can be automatically or manually accounted for in the zeroing.

The working end of the instrument 10, with or without a distal guide170, can be placed next to the exposed and dissected bone and theinstrument zeroed. Alternatively, the user can extend a few millimetersof the working tool 110 to engage the bone and drill a counter-sink orpilot hole prior to zeroing the instrument 10. Where a fixation plate isused, the plate can be placed next to the bone and the drill end placedsnug to the plate. Alternatively, some plates have guides that interfacesuch that the instrument is directed at a selected angle. Theinstruments disclosed herein can be made such that they attach to orfreely engage these types of distal guides 170.

The user can apply pressure axially and engage first the rotationaldrive motor 60 to the desired speed. The user can proceed to engage theaxial drive motor 30 either continuously or incrementally, dependingupon the material strength and bone density and preference of the user.The drilling can continue through the cortical bone, through themedullary canal or cancellous bone, into and through the distal corticalbone. Once through the distal cortical bone as determined by pre-setdepth control mechanism, axial resistance, auditory feedback from therotational speed of the drill bit and/or auditory feedback fromacceleration or torque sensors, the axial movement can be stopped. Theuser can remove the working tool 110 by reversing the axial drive motor30 or by pulling back on the instrument 10. The rotational drive motor60 can be left engaged and in the forward direction to facilitateclearing the hole created. The user can read the depth on the display236 and select the proper screw for implantation. The screw can beimplanted using a screw driver or the like. In another method, the usercan perform a unicortical procedure wherein the working tool is stoppedprior to some other endpoint such as before or after a growth plate orbefore or after the distal cortex.

In use, an instrument 10, such as the instrument shown in FIG. 4, can beset against exposed bone or, if used, the fracture fixation plate orother type of implant such as a joint prosthetic. The appropriatezero-depth position can be determined automatically. Once the useractivates the trigger 232, the guide 170 as well as the guides 300, 302retracts in the proximal direction (arrow P) and the working tool 110can extend through the guide 170. The working tool 110 can engage thework and bore into the work as the user applies pressure to theinstrument 10 and keeps it engaged with the work. The working tool 110can drill into the bone by the amount the guide 170 retracts. The guide170 retraction can be measured instantaneously and shown on a display,for example a display positioned at the back of the instrument 10. Theautomatic determination of the zero-position whether set against bone oragainst a fracture fixation plate can depend upon algorithms related tothe way the guide 170 sets against the bone or the plate and thethickness of the plate. These variables can be unique to each platingsystem and set of guides. The depth of the travel of working tool 110into the work, and/or the instantaneous torque or torque curve, can bemeasured and shown on the display 236 simultaneously and instantaneouslyas the working tool 110 moves axially in a distal direction andpenetrates the work.

Once the desired depth of penetration is reached, the reverse trigger234 can be actuated to cause both of the drive motors 30, 60 to reversetheir direction. The action of the axial drive motor 30 can cause thedrive lug 240, the rear surface guide 300, the forward surface guide 302and the guide 170 to move in an axial direction away from the body 20 ofthe instrument 10 in a distal direction such that the axial movementpushes the instrument body 20 away from the work and draws the tool 110out of the work. Alternatively, the operator can pull the tool 110 fromthe work with the instrument either on (in any direction) or off.

Aspects of the subject matter described herein may be realized indigital electronic circuitry, integrated circuitry, specially designedASICs (application specific integrated circuits), computer hardware,firmware, software, and/or combinations thereof. These variousimplementations may include implementation in one or more computerprograms that are executable and/or interpretable on a programmablesystem including at least one programmable processor, which may bespecial or general purpose, coupled to receive data and instructionsfrom, and to transmit data and instructions to, a storage system, atleast one input device, and at least one output device. For example, asoftware program can be incorporated into the device that takesadvantage of the reproducible relationship between current, torque,material strength and density in a system where the RPM of therotational motor is held constant. Current is proportional to torque andtorque is proportional to bone strength and density. As such thesoftware can correlate the current the motor uses during drilling orsawing to the material strength and bone density. Such a softwareprogram can be used to measure material strength and bone density inreal-time by reading the current being used by the motor. The softwareprogram can also be used to control RPM, feed rate, current and/orvoltage.

These computer programs (also known as programs, software, softwareapplications or code) include machine instructions for a programmableprocessor, and may be implemented in a high-level procedural and/orobject-oriented programming language, and/or in assembly/machinelanguage. As used herein, the term “machine-readable medium” refers toany computer program product, apparatus and/or device (e.g., magneticdiscs, optical disks, memory, Programmable Logic Devices (PLDs)) used toprovide machine instructions and/or data to a programmable processor,including a machine-readable medium that receives machine instructionsas a machine-readable signal. The term “machine-readable signal” refersto any signal used to provide machine instructions and/or data to aprogrammable processor.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of the claims or of what can beclaimed, but rather as descriptions of features specific to particularembodiments. Certain features that are described in this specificationin the context of separate embodiments can also be implemented incombination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesub-combination. For example, a current sensing mechanism can beincorporated into a drill or saw device and used independently of adepth-control mechanism. Similarly, a depth-control mechanism can beincorporated into a device that does not include other sensingmechanisms. Moreover, although features can be described above as actingin certain combinations and even initially claimed as such, one or morefeatures from a claimed combination can in some cases be excised fromthe combination, and the claimed combination can be directed to asub-combination or a variation of a sub-combination. Similarly, whileoperations are depicted in the drawings in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results.

Although embodiments of various methods and devices are described hereinin detail with reference to certain versions, it should be appreciatedthat other versions, embodiments, methods of use, and combinationsthereof are also possible. Therefore the spirit and scope of theappended claims should not be limited to the description of theembodiments contained herein.

What is claimed is:
 1. A driving device comprising: a housing having aproximal end and a distal end; a motor contained within the housing; agearbox connecting the motor to a working tool interchangeably connectedvia a coupler, wherein the motor turns the gearbox, the coupler and theworking tool; a torque sensor configured to measure drilling torque atan output of the gearbox and convert the measured drilling torque into atorque measurement signal, wherein the drilling torque is in a directionopposite rotation of the working tool, wherein the gearbox has a gearboxtorque in a direction opposite rotation of the working tool producing agearbox loss, and wherein the gearbox is held as a reference point suchthat the gearbox loss is excluded from the torque measurement signal;and a tool guide assembly coupled to the housing, the tool guideassembly comprising: a tool guide configured to surround at least aportion of the working tool; and a surface guide having a proximalregion and a distal region, the distal region configured to couple tothe tool guide and the proximal region configured to couple to thehousing, wherein upon actuation, axial motion of the tool guide assemblytowards the proximal end of the housing to a retracted state allows alength of the working tool to be driven into a target region of work. 2.The device of claim 1, further comprising a programmable electronicspackage in communication with the torque sensor.
 3. The device of claim2, wherein a change in the torque measurements corresponds to change inmaterial strength and density of work penetrated.
 4. The device of claim3, further comprising an alert, wherein the torque sensor communicateswith the programmable electronics package in real-time and the alertprovides a user with information regarding status of the driving deviceduring use.
 5. The device of claim 4, wherein the alert comprises anauditory, visual or tactile signal.
 6. The device of claim 3, whereinthe work penetrated comprises medullary canal, cancellous bone, corticalbone, or soft tissue.
 7. The device of claim 1, wherein the working toolis selected from the group consisting of a drill bit, a detuned drillbit, wire, Kirschner wire, pin, trochar, burr, screwdriver, reamer, saw,saw blade, router, router bit, stepped drill bit, bone plug removaltool, bone harvesting tool, bone marrow harvesting tool, and bone marrowaspirating tool.
 8. The device of claim 2, further comprising one ormore axial force sensors configured to sense the axial force applied atone or both of the distal end of the tool guide and the working tool. 9.The device of claim 8, further comprising an axial force alert, whereinthe axial force sensor communicates with the programmable electronicspackage in real-time and the axial force alert provides a user withinformation regarding status of the driving device during use.
 10. Thedevice of claim 9, wherein the axial force alert comprises an auditory,visual or tactile signal.
 11. The device of claim 10, wherein the visualsignal comprises one or more LEDs positioned within a userline-of-sight, wherein the LEDs indicate degree of axial force beingapplied by the user to the tool guide in real-time.
 12. The device ofclaim 2, wherein the one or more axial force sensors comprises a toolguide sensor configured to sense and signal the axial force applied bythe user to the tool guide.
 13. The device of claim 12, wherein the oneor more axial force sensors comprises a working tool sensor configuredto sense and signal the axial force applied by the user to the workingtool, wherein the degree of axial force being applied to the tool guideis provided separately from the degree of axial force being applied tothe working tool.
 14. The device of claim 13, wherein the degree ofaxial force being applied to the tool guide and the degree of axialforce being applied to the working tool equals the total user forceapplied to the device.
 15. The device of claim 1, wherein the tool guideat least partially surrounding the working tool is configured to assistin the engagement of an implant.
 16. The device of claim 15, wherein thetool guide comprises one or more features that mechanically couple withcorresponding features of the implant.
 17. The device of claim 15,wherein the implant comprises a fracture fixation plate or a joint part.18. The device of claim 15, wherein the tool guide couples to theimplant at an angle away from perpendicular.
 19. The device of claim 2,wherein a change in current used to drive the motor is received by theprogrammable electronics package signaling when to stop the axial motionof the tool guide assembly and preventing penetration of the workingtool beyond the target region of the work.
 20. The device of claim 1,wherein the torque sensor is coupled to the housing and to the motorsuch that the torque sensor couples the motor to the housing.
 21. Thedevice of claim 1, further comprising a second motor contained withinthe housing, wherein the proximal region of the surface guide is coupledto the second motor.
 22. The device of claim 21, wherein the secondmotor is configured to cause the axial motion of the tool guide assemblytoward the proximal end of the housing.
 23. The device of claim 21,wherein the first motor is coupled to a first drive shaft and the secondmotor is coupled to a second drive shaft.
 24. The device of claim 23,wherein the first drive shaft and the second drive shaft are in aco-axial, parallel, or orthogonal arrangement relative to one another.25. The device of claim 23, wherein the surface guide comprises aforward surface guide and a rear surface guide, wherein a distal regionof the forward surface guide couples to the tool guide and a proximalregion of the forward surface guide couples to the rear surface guide,and wherein the rear surface guide couples to the second drive shaft.26. The device of claim 25, wherein the rear surface guide is attachedto a drive lug coupled to and powered by the second motor to move therear surface guide in an axial direction.
 27. The device of claim 25,wherein the forward surface guide comprises at least one support thatmates with corresponding support of the rear surface guide.
 28. Thedevice of claim 25, wherein the forward surface guide engages an outersurface of the coupler.
 29. The device of claim 1, wherein the toolguide assembly is configured to be removed away from the working tool.30. The device of claim 1, wherein contact between the tool guideassembly and the working tool is prevented by maintaining the tool guideassembly coaxial with a longitudinal axis of the working tool.